1. Field of the Invention
The present invention relates to a device for use in traps for monitoring and/or capturing pest flying insects. The device permits uniform, extended emissions of an insect attractant in amounts that are attractive to the targeted flying insect.
2. Description of the Related Art
Insect lures (attractants) are currently employed to detect and monitor for the presence of insects that respond to lure-baited traps, such as for example, the Mediterranean fruit fly (medfly), melon fly, codling moth, mosquito, etc. Lures emitted from insect traps travel downwind for great distances which allow monitoring traps to be placed as much as a mile apart. Responding insects, on detecting the lure scent, fly upwind until they locate the trap, enter it, and are caught. If the responding insect loses the scent, it will circle back and forth cross-wind until it again locates the scent and then continue to move toward the lure in the trap. Insects are extremely sensitive to lures especially sex lures which help insects find the opposite sex for mating and propagation. Male gypsy moths, for example, have been found to respond to 1 ng of suitably formulated DISPARLURE (gypsy moth pheromone) in traps for 3 months in the field (Beroza et al., J. Econ. Entomol., Vol. 64, 1499-1508, 1971). Insects will not enter a trap if lure emission is too high and they will have difficulty finding the trap if lure emission is too low. For maximum efficiency with a given trap, the lure level must be as high as possible in order to draw the targeted insects from as far away as possible but not so high as to repel or prevent the responding insect from entering the trap. The information derived from the lure-baited traps is used to determine where and when control measures are needed, such action being more environmentally friendly and cost effective than widespread application of insecticides used in the past. Such control measures can include insecticide application, sterile-insect release, mass trapping, etc. For medflies, traps are manually examined every two to three weeks to see if any insects are in the traps and to rebait the traps. Targeted pests, such as for example, the Mediterranean fruit fly (Medflies), cause damage to fruits and vegetables during the course of a season that has been estimated to amount to millions of dollars. In order to effect control of these targeted pest insects, it is necessary to locate the area and determine the degree of infestation. This may be done by setting out traps in suspected areas and placing in the traps a bait and/or attractant for the targeted pest. In the case of Mediterranean fruit flies, approximately 150,000 traps containing the attractant TRIMEDLURE are deployed in California. If Medflies should come into the United States and are trapped, thousands more traps will be deployed in a mass trapping effort to confine the flies in one area where they can be destroyed. Over one million TRIMEDLURE plugs are sold in the United States each year to keep the traps effective.
Wick-based, liquid emanation systems are known. Typically, in such systems, one end of a wick is partially submerged in a liquid to be dispensed. The liquid is contained in any suitable container. The partially submerged portion of the wick absorbs the liquid, some of which diffuses by capillary or wicking action into the exposed portion of the wick. In prior art systems, the exposed portion of the wick is heated, often by means of a ring-shaped heater which fits over the wick.
In other systems, a liquid containing a scent or pheromone is poured onto an absorbent material such as a wick. The wick is then placed in a trap and there is no way to control the amount of scent or pheromone being released thus resulting in expensive waste. Furthermore, emission rates decline rapidly over time. For example, TRIMEDLURE, a Mediterranean fruit fly lure, is absorbed on a cotton plug that emits TRIMEDLURE at an ever-declining rate resulting in the plug replacement every 2-3 weeks.
There remains a need in the art for an effective flying insect attractant emission device which delivers flying insect attracting amounts of an attractant at constant emission rates, i.e., at the lure=s most attractive level, over extended periods of time. The present invention provides a device that improves the trapping efficiency of insect traps by providing a constant emission rate of insect attracting amounts of a composition containing at least one flying insect attractant over periods of time greater than that achieved by prior art devices and is different than prior art devices used for insect lures.